G2417.7.1 (406.7.1) Piping Systems Required to Be Purged Outdoors
- The design operating gas pressure is greater than 2 psig (13.79 kPa).
- The piping being purged contains one or more sections of pipe or tubing meeting the size and length criteria of Table G24126.96.36.199.
Where existing gas piping is opened, the section that is opened shall be isolated from the gas supply and the line pressure vented in accordance with Section G24188.8.131.52. Where gas piping meeting the criteria of Table G24184.108.40.206 is removed from service, the residual fuel gas in the piping shall be displaced with an inert gas.
TABLE G24220.127.116.11 (406.7.1.1)
SIZE AND LENGTH OF PIPING
|NOMINAL PIPE SIZE|
|LENGTH OF PIPING |
|≥ 21/2 < 3||> 50|
|≥ 3 < 4||> 30|
|≥ 4 < 6||> 15|
|≥ 6 < 8||> 10|
|≥ 8||Any length|
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
- CSST EHD size of 62 is equivalent to nominal 2-inch pipe or tubing size.
The open end of a piping system being pressure vented or purged shall discharge directly to an outdoor location. Purging operations shall comply will all of the following requirements:
- The point of discharge shall be controlled with a shutoff valve.
- The point of discharge shall be located not less than 10 feet (3048 mm) from sources of ignition, not less than 10 feet (3048 mm) from building openings and not less than 25 feet (7620 mm) from mechanical air intake openings.
- During discharge, the open point of discharge shall be continuously attended and monitored with a combustible gas indicator that complies with Section G2418.104.22.168.
- Purging operations introducing fuel gas shall be stopped when 90 percent fuel gas by volume is detected within the pipe.
- Persons not involved in the purging operations shall be evacuated from all areas within 10 feet (3048 mm) of the point of discharge.